2001 315r Falling on its face in 3rd-5th

[sherco29]

Just picked up a well used 2001 315r.

Trying to get it running right.

Got a chance to take it out to the woods today and in 1st and 2nd all is well.

Get on a dirt road and take it up to 3rd and 4th and it wont take any throttle. Starts cutting out and bucking and wanting to die.

Only seems to do this once its up to temp. Which sorta makes testing potential fixes a pita.

So far I have been through the carb twice...its spotless. Tried the floats every which way and didnt make a difference.

Need to pick up a new spark plug tomorrow as everywhere was closed on Sunday here. Old plug doesnt look to hot. But not sure if thats related.

Anyways...looking for other ideas. I am about 2000 feet higher here than it was run...but have brought several bikes over from that area and they always run ok...usually need to drop the mains 2 sizes. But they always run ok just a lil rich.

I just noticed looking at my 02 manual that I may be missing the sub air filter? I did not see any nipple for it on the carb? Did 01's have that?

Any wisdom appreciated. I am pretty new to 2 strokes so I am still learning here!

Edited November 15, 2010 by sherco29

[jordi]

Just picked up a well used 2001 315r.

Trying to get it running right.

Got a chance to take it out to the woods today and in 1st and 2nd all is well.

Get on a dirt road and take it up to 3rd and 4th and it wont take any throttle. Starts cutting out and bucking and wanting to die.

Only seems to do this once its up to temp. Which sorta makes testing potential fixes a pita.

So far I have been through the carb twice...its spotless. Tried the floats every which way and didnt make a difference.

Need to pick up a new spark plug tomorrow as everywhere was closed on Sunday here. Old plug doesnt look to hot. But not sure if thats related.

Anyways...looking for other ideas. I am about 2000 feet higher here than it was run...but have brought several bikes over from that area and they always run ok...usually need to drop the mains 2 sizes. But they always run ok just a lil rich.

I just noticed looking at my 02 manual that I may be missing the sub air filter? I did not see any nipple for it on the carb? Did 01's have that?

Any wisdom appreciated. I am pretty new to 2 strokes so I am still learning here!

Have a check to ensure there is no blockage in the petrol tap its self, sounds as if it could be fuel starvation.

Edited November 15, 2010 by jordi

[wherry]

sounds as if it could be fuel starvation.

That's kind of what it sounds like to me too.

Have you checked and cleaned the plastic filter in the fuel-in banjo on the carb?

[monteberg]

as jordi says check fuel supply I kinked feed from tap to carb once fitting tank .didnt stop fuel completely but restricted it enough to give symptoms like yours also make sure the breather in tank cap is clear fling the old plug away and fit new with new cap and ht lead ,latter is a quick and cheap job and should be considered as routine maintenance hope this helps ya out

[sherco29]

Have good fuel flow from the tank to carb...vents clear.

Got some new plugs...trying to figure out a way to rig a sub air filter till I can source a proper one. Dunnu wtf the PO was thinking not having that installed as the hole in the carby was stuffed full of crap where its supposed to go. Suprised it idled as good as it did? Ugggg.There is no nipple on the carb anymore...just a hole. WTF.Hose and filter are MIA, only the bracket remains.

Also trimmed a bit of the plug lead and re-fit the cap. Need to come up with something to keep the dirt out of the carb where the missing sub filter is supposed to be...may just stuff a bit of foam in the hole for now. Want to try to get this thing running before I start spending any real $$ on it! But dont want to go ride it w/o something in that hole in the side of my now spotless carby!

Edited November 15, 2010 by sherco29

[dgshannon]

I just noticed looking at my 02 manual that I may be missing the sub air filter?

Owned many 315's and I am not familiar with the term "sub air filter". What are you referring to.

[sherco29]

The small air filter that runs from opposite the air screw on the carb body up to near the rear brake master resevoir under the seat. Page 21 of the 02 manual you can see #13 pointing to the hose for it. (the call it a sub air cleaner)

I went to the auto parts shop and found a plastic fitting that I sanded to press fit the hole in the carb, ran a hose from that to a filter under the seat for now.

Fresh plug...bikes loaded...fingers crossed! Seemed good in my driveway but cant open it up here. Headed for the local play area.

Here is a pic of my jimmy-rigged sub air filter...

Curious if I order the filter/housing, and hose will it come with a fitting to press into the hole in the carb? No threads there?

Edited November 15, 2010 by sherco29

[sherco29]

It runs! I trimmed a bit off the HT lead and screwed the cap back on. Tossed a new plug in and she pulls good in all gears.

Now I need to fix the leaky fork seals, and the squealing clutch.